Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

Update: West Nile Virus Activity --- United States, 2005

This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Daylight Time, September 13, 2005.

Thirty-seven states have reported 1,299 cases of human WNV illness in 2005 (Figure and Table 1). By comparison, in 2004, a total of 1,386 WNV cases had been reported as of September 14, 2004 (Table 2). A total of 671 (56%) of the 1,193 cases for which such data were available occurred in males; the median age of patients was 50 years (range: 3 months--98 years). Date of illness onset ranged from January 2 to September 8; a total of 29 cases were fatal.

During 2005, a total of 230 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET. Of these, 71 were reported from California; 37 from Nebraska; 32 from Texas; 20 from South Dakota; 15 from Louisiana; nine from Kansas; seven from Iowa; six each from Arizona and Illinois; five from New Mexico; four from Minnesota; three from Oregon; two each from Alabama, Colorado, Mississippi, and Utah; and one each from Idaho, Michigan, Montana, Nevada, North Carolina, North Dakota, and Pennsylvania. Of the 230 PVDs, four persons aged 35, 53, 56, and 71 years subsequently had neuroinvasive illness; three persons aged 17, 41, and 51 years subsequently had other illnesses; and 60 persons (median age: 47 years [range: 17--78 years]) subsequently had West Nile fever.

In addition, 2,926 dead corvids and 627 other dead birds with WNV infection have been reported from 39 states. WNV infections have been reported in horses from 28 states, three dogs from Minnesota and Nebraska, four squirrels from Arizona, and two unidentified animal species in two states (Arizona and Illinois). WNV seroconversions have been reported in 675 sentinel chicken flocks from 12 states. One seropositive sentinel horse was reported from Minnesota. A total of 7,822 WNV-positive mosquito pools have been reported from 38 areas (Alabama, Arizona, Arkansas, California, Colorado, Connecticut, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, and Wisconsin).

Additional information about national WNV activity is available from CDC at and at


Return to top.
Table 1

Table 1
Return to top.
Table 2

Table 2
Return to top.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

All MMWR HTML versions of articles are electronic conversions from typeset documents. This conversion might result in character translation or format errors in the HTML version. Users are referred to the electronic PDF version ( and/or the original MMWR paper copy for printable versions of official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO
A-Z Index
  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #